Maximum notifications frequency

[dblasco]

Hello everyone,

I am doing a project in which a nRF58122 is getting data of an accelerometer and an ADC. Those can be set a really high frequencies. The problem is, when I want to send the information through BLE to an android device. I send notifications of two characteristics (one 6 bytes and the other one 2 bytes).

If I take, for example, a frequency data rate of 20 Hz, I lose lots of packets. Is it normal? Which should be the maximum notification frequency before beginning to lose packets?

This is some code I use for the notification. This timer handler is called every time I want o send the notification again, for example every 0.05s (at 20Hz).

    void timer_iforce_handler(void * p_context)
{
	
	UNUSED_PARAMETER(p_context);
	
	uint16_t len;
	
	
	// Accelerometre notification
	len=6;
	readAccelData();
	
	//Notification
	ble_gatts_hvx_params_t hvx_params;
    memset(&hvx_params, 0, sizeof(hvx_params));

    hvx_params.handle = m_iforce.iforce_accelerometer_handles.value_handle;
    hvx_params.type   = BLE_GATT_HVX_NOTIFICATION;
    hvx_params.offset = 0;
    hvx_params.p_len  = &len;
    hvx_params.p_data = accelData;

    sd_ble_gatts_hvx(m_zipconfig.conn_handle, &hvx_params);
	
	// ADC notification
	
	len=2;
	ADS1120_check_and_read();
	
   //Notification

    memset(&hvx_params, 0, sizeof(hvx_params));

    hvx_params.handle = m_iforce.iforce_straingauge_handles.value_handle;
    hvx_params.type   = BLE_GATT_HVX_NOTIFICATION;
    hvx_params.offset = 0;
    hvx_params.p_len  = &len;
    hvx_params.p_data = rx_buffer;

    sd_ble_gatts_hvx(m_zipconfig.conn_handle, &hvx_params);
	
}

Thank you very much!

[Petter Myhre]

The S110 peripheral SoftDevice can send 6 notifications in each connection interval. The minimum connection interval is 7.5 ms. So if the central also supports this you can achieve

6/0.0075 = 800 notifications/sec.

Please see this question for how to set it up.

You shouldn't lose any packets, maybe you can edit your question to include code on how you are doing this?

[Petter Myhre]

You can use a sniffer, for example the nRF Sniffer, or you can do what is descibed here.